The present invention relates generally to the field of agricultural implements such as planters, seeders and other wide, foldable implements towed behind a work vehicle, such as a tractor. More particularly, the present invention relates to a telescoping drive shaft for use within the foldable implements towed behind the work vehicle.
A wide range of farm implements have been developed and are presently in use for tilling, planting, harvesting, and so forth. Seeders or planters, for example, are commonly towed behind tractors and may cover wide swaths of ground which may be tilled or untilled. Such devices typically open the soil, dispense seeds in the opening, and reclose the soil in a single operation. Seeds are commonly dispensed from seed tanks and distributed to row units by a distribution system. To make the seeding operation as efficient as possible, very wide swaths may be covered by extending wings on either side of a center section of the implement pulled by the tractor. Included in the wing assemblies are tool bars, row units mounted thereon, and support wheels. The wings and row units are commonly disposed in a “floating” arrangement during the planting operation, wherein hydraulic cylinders allow the implement to contact the soil with sufficient force to open the soil, dispense the seeds and close the soil. For transport, the wings may be elevated by the support wheels to disengage the row units from the ground and folded forward to reduce the width of the implement
The foldable wing assemblies include multiple row units configured to deposit seeds within the soil with a metering system. Each of the row units uses a rotatable power source to power the metering system, such as an electrical or hydraulic motor, or a drive wheel. The power source may be from an external source, or may be positioned on the center section. In particular, various shafts are typically used within the wing assemblies to transfer rotational power from the power source and through the length of the tool bars and/or between adjacent row units. Multiple primary gearboxes are rotatably coupled to the shafts, which are then configured to use the rotation for driving downstream components within the row unit, such as the metering system. Typically, standard shafts are limited to the amount of space provided within the region of the wing assemblies where these drive shafts must fit. Further, standard shafts may be fixed in length, providing little extension or retraction movement.
However, drive shafts within the wing assemblies often desire flexibility as the wing assemblies transition between, for instance, ground engaging positions and transport positions. For example, in certain situations, a drive shaft disposed at pivot locations on the agricultural implement, such as between the power source on the center section and each wing assembly, may transfer rotational power. Unfortunately, given the limited extension and retraction the standard drive shaft provides, the drive shaft may be restricting the movement of the wing. Further, in some circumstances, the row units may need to be periodically separated sufficiently enough for maintenance and servicing operations (e.g., emptying, cleaning, etc.). However, given the standard drive shaft's limited freedom of movement, it may be difficult to separate row units without disconnecting rotational power. As such, it may be desirable to provide a drive shaft with a greater amount of extension and retraction flexibility.